Genetic and microbial effects on aggressive behavior

Aggression is a behaviour expressed throughout the animal kingdom in various situations such as foraging or the protection of offspring and territory. It is also an important and normal component of the human behavioural repertoire, but excessive aggression that can occur in the course of neurological or psychiatric disorders is detrimental for the affected individuals, society and healthcare providers. The reasons why some people are prone to aggression and others not are complex. It is thought that genetics plays an important role for the development of aggression, but environmental factors are equally important. This necessitates a better understanding of the biological basis of aggression, which may ultimately lead to novel therapeutics for affected individuals. We will study aggression with the help of zebrafish, a small freshwater fish species that exhibits a wide range of behaviours including aggression. To investigate genetic factors leading to aggression, we will use the gene scissor CRISPR-Cas9 to find genes that increase or decrease aggression levels. We will then analyse brain areas activated by aggression to understand how genetic changes are translated into altered behaviour. In the second part of the project, we will analyse how non- genetic factors affect aggression, with a focus on the gut microbiota. This term describes the whole microbial community within the gut including bacteria, virus and fungi. It is known that these microorganisms are essential for regulating the activity of the immune system or the processing of ingested food. However, an exciting novel line of research suggests that gut microbiota can influence the function of distant organs such as the brain. Via the so-called microbiota-gut-brain axis, microbial signals are thought to alter brain function and neurobiology. For example, psychiatric disorders such as depression have been linked to microbial community disturbances and probiotics can exert beneficial effects on mental health. We will therefore investigate, if and how microbiota influence aggressive behaviour and whether microbiota-based therapies can be used to counteract excessive aggression. Taken together, this project aims to advance our current understanding of aggression genetics and to determine the relevance of intestinal microbiota in the context of aggression. It has the potential to uncover novel genes associated with aggression and to help in the development of novel therapeutic strategies.